Electric heating apparatus



R. P. DUNNING.

ELECTRIC HEATING APPARATUS.

APPLICATION FILED JUNE 2l, 1920.

1,362,609 Patented D9@ 2L @2%.

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UNiTsn y STATES PATENT GFFEC.

RAYMOND P. DUNNING, F SCHENECTADY, YORK, ASSIGNOR T0 GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATING A'lll?ARATUS.

Application filed .Tune 21, 1920.

To all whom t may concern:

Be it known that I, RAYMOND P. DUNN- ING, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State-of New York, have invented certain new and useful Improvements in Electric Heating Apparatus, of which the following is a specification.

My invention relates to electric heating apparatus and particularly to a device for heating rivets and the like articles by passing current therethrough.

An object 0f my invention is to provide a device of the class described which shall be simple and rugged in construction and which shall permit of rapid and economical operation by unskilled. labor without danger of burning the articles to be heated. l

My invention will be better understood from the following description taken in con nection with the accompanying drawing, and its scope will be pointed out in the appended claims. l

Referring to the accompanying drawing, Figure 1 is a perspective view of an elec tric heating device embodying my invention, parts being broken away to show the constructionl more clearly; Figs. 2, 3 and 4f are circuit diagrams.

Referring to Fig. 1, a shell type transf former is illustrated provided with a primary winding 1 on the center leg 2 of the laminated core structure, the outside legs 3 and 4 being left unwouiid. Electrodes 5, 6, 7 and 8 are mounted respectively on conducting bars 9, 10, 11 and 12 preferably' made of copper, which are independently movable in the windows of the transformer core. These bars are pivotally mounted on the rod 13 in the rear of the device, the rod 13 being secured to and insulated from the cross piece 14 mounted on the angle iron supporting frame which comprises front legs 15|, 16 and rear legs 17, 18 with suitable bracing members. The transformer core is mounted in any suitable manner upon this frame structure. One pair of bars 9 and 12 are connected together by a flexible laminated conductor 19 and the other pair of bars 10 and 11 are connected together by a similar flexible conducting means 20. The pairs of conducting'bars 9, 12 and 10, 11 constitute secondary windings for the transformer, current being directly induced in these bars by the alternating Specification o Letters Patent.

Patented Dec. 21, 1920.

Serial No. 390,518.

flux set up in the primary winding 1 which may be connected to any convenientsource of supply. The rod 13 passes through equipotential points of the transformer windings 9, 12 and 10. 11 and it is therefore unnecessary to insulate these bars from the rod 13. The mid points of the flexible connectors 19 and 2O are electrically connected together by rivets 21 for a purpose hereinafter described. The electrodes 5, 6, 7 and 8 aie preferably made of copper blocks secured t0 the pivoted bars in any suitable manner, bolts 22 being shown in the drawing for this purpose. A stationary conducting member or electrode 23 is provided below and in coperative relationship with the movable electrodes, and the articles 24 to be heated are interposed between the contact faces of the electrodes .5, 6, 7 and 8 and the contact face of the electrode 23. The contact faces of the movable electrodes are preferably curved to enable articles of any convenient length to be interposed between them and the electrode or conducting member 23. The electrode 23 is supported on a member 25, an insulating member 26 being used to insulate the member 23 from the member 25. The member 25 is adjustably mounted upon the angle iron 27 of the frame by means of bolts provided with wing nuts 28, the bolts being arranged in slots 29 provided iii the member 25. The pivoted electrode carrying bars are arranged to be moved to raise and lower the same to permit of inserting and withdrawing the articles to be heated. As represented in the drawing, this movement is secured by means ofpivoted foot levers 30 connected through rods 31 to the respective bars 9, 10, 11 and 12. Insulating joints 32 are provided in the rods 31. The arrangement is such that when an article to be heated is removed, the foot levers 30 engage the cross piece 33 of the frame so that the downward movement of the electrode is limited. In this way, a short circuit of the transformer secondary winding is prevented when the articles to be heated are removed.

To operate the arrangement shown in Fig. 1, the operator depresses the foot levers 30 and interposes the articles to be heated between each of the movable electrodes 5, 6, 7 and 8 and the conducting member 23. No circuit is completed when articles are inserted under electrodes 5 and 6 only.

Upon inserting an article under electrode 7, a circuit is made through the bars 9 and 10 which is completed through the bar 11. The current thus Hows in parallel through two articles to be heated and thence in series through the single article inserted under electrode 7. When an article is also inserted under electrode 8, the current through all of the articles to be heated is the same. The secondary winding of the transformer composed of bars 9 and 12 feeds current to two articles in series while the secondary Winding composed of bars 10 and 11 feeds current to the other two articles in series.

` The broad idea of series heating in this 1919 and the .idea of a secondary winding comprising electrode carrying bars independently movable in the windows of the transformer core is claimed in the copending application of Edgar F: Collins. Serial No. 325,656, filed September 23, 1919, assigned to the assignee of this application. According to my invention, however, the conducting bars are arranged in al plurality of pairs which are electrically interconnected so that a circuit may be completed through electrodes carried by bars belonginto different pairs.

ig. 2 is a circuit diagram indicating the principle of heating articles represented as rivets 34 and 35 in series. Current fiows from one terminal of the secondary winding 36 of the transformer whose primary is represented at 37 through the electrode 38, rivet 34, conducting member 39, rivet 35 and electrode 40 back to the other terminal of the secondary 36. Thenever one of the rivets becomes heated, it is removed and another rivet interposed. During this time the circuit is interrupted and the heating is discontinued. This is not without some advantage, however, for the reason that it permits the heat to become uniformly distributed throughout the remaining rivet so that the final heating given after the insertion of the new rivet produces a rivet heated uniformly throughout its length. The capacity of this type of heater can, of course, be increased by supplying two such series circuits in multiple as indicated in Fig. 3, wherein one terminal of the transformer secondary 41 is connected in multiple to the electrodes 42 and 43,

vthe circuits being lcompleted through the conducting members 44 and 45 and electrodes 46 and 47 connected to the other terminal of the secondary 41.

According to my invention, the circuit need never be interrupted during the norlmal operation of the apparatus `although the advantages vincident to series heating are retained. This will be apparent when it is observed that when one article is removed, the voltage drop is redistributed over the remaining articles so that the voltage across the articles, which carry current in parallel, is reduced, while the voltage across the article which carries the current from the parallel articles is increased. This permits the heat to distribute itself throughout the articles which are carrying current in parallel and gives a slightly increased heating to the article carrying the current from the parallel articles. Should one of the articles be covered with a small amount of scale so that it tends to interrupt the circuit at this point the voltage will rise across this article to break down the initial resistance to the flow of current. Furthermore, should one of two parallel articles tend t0 heat -more than the other` the increase of its resistance tends to cause current to How in the parallel path through the other article, thus producing an equalizing effect upon the heating currents. inasmuch as the circuit is never interrupted, the heating always continues even when the operator removes an article from the machine, and in this waythe output of the machine is considerably increased.

It is apparent that while my invention is particularly adapted to an arrangement, such as shown in Fig. 1, in which the voltage is induced directly in the electrode carrying members, the principle of in v invention may be carried out in an arrangement, such as shown in Fig. 4, wherein the voltage is developed in a transformer separate from the heating apparatus. In Fig. 4. the transformer having the primary winding 48 is provided with two secondary windings 49 and 50, the equipotelitial points of which are connected by`a' conductor 51. The terminals of winding 49 are connected to electrodes 52 and 53 to supply current thereto in series, while the secondary winding 50 is connected to the electrodes 54 and 55 to supply current to these electrodes in series. -A conducting member 56 is provided between which and the movable electrodes, the articles to be heated, are adapted to be inserted. It is apparent that if articles are interposed between conducting member 56 and electrodes 52 and 55 only, a circuit will be completed from the mid point of winding 49 through one half of this winding to electrode 52 through the articles to be heated and back through one half of winding 50 and the connection 51 to the starting point. This circuit corresponds to the circuit in Fig. 1 traced from point 21 through bar 9i. electrode 5 and the articles 'to be heated, electrode -7 and bar 11 back to the starting point 21.

What 1 claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric heating apparatus of the class described comprising a plurality of pairs of electrodes, means whereby said electrodes may be independently moved, conducting means between which and said movable electrodes the articles to be heated are .adapted to be interposed, means corresponding to each pair of electrodes for producing an M. F. to supply current in series through the corresponding pair of electrodes and the interposed articles to be heated and means electricallly connecting equipotential points in said M. F. producing means whereby a circuit may be completed through articles interposed between said conducting means and electrodes belonging to different pairs.

2. An electric heating apparatus of the class described comprising a transformer winding composed of a plurality of pairs of movable conducting bars carrying electrodes, means whereby a circuit may be completed in series through a pair of said electrodes and a plurality of articles to be heated, and means for interconnecting said pairs of bars whereby articles may beheated in a circuit completed through electrodes carried by bars belonging to diii'erent pairs.

3. An electric heating apparatus of the ,class described comprising a transformer *winding composed of a plurality of pivoted bars carrying electrodes, curvedV laminated V'flexible conducting means connecting said bars in pairs and secured adjacent the pivotpoints of the bars, a conducting member between which and the electrodes the articles to be heated are adapted to be interposed to complete series circuits through sa1d pairs of bars and articles to be heated,` and means electrically connecting the mid points of said laminated cpnnecting lmeans whereby a circuit maybe completed through articles interposed between said conducting member for independent movement in/ the windows of said core and adapted to act as parts of the secondary winding of said transformer, conducting means connecting said bars in pairs while permitting independent movement thereof, electrodes mounted on said bars, a conducting member between which and said electrodes the articles to be heated are adapted to be interposed whereby series circuits maybe completed through the bars of each pair and the interposed articles, and means for interconnecting said pairs of bars so that circuits for heating interposed articles may be completed through bars belonging to different pairs.

5. An electric heating apparatus of the class described comprising a transformer Winding composed of a plurality of independently movable bars carrying electrodes arranged to engage articles to be heated characterized by the fact that connections are provided whereby current may iiow in series through the articles to be heated in a plurality of circuits in multiple and through circuits-comprising a plurality of articles in parallel in series with another article.

In witness whereof I have hereunto set my hand this 18th day of June, 1920.

RAYMoND P. DUNN'ING. 

